1. Field of the Invention
This invention relates to an improved method of forming a gravel pack wherein particulate material, such as sand, electrolessly-coated with copper, is injected as a slurry into the well to form a deposit against the wall of the well bore and subsequently electrolessly plating the in-place, coated sand with, for example, nickel thus forming a consolidated, permeable, metal-coated sand pack which is effective in preventing the flow of fine particles from the formation into the well.
2. Prior Art and Background
Recovery of formation fluid such as petroleum from a subterranean formation is frequently difficult when the subterranean formation is comprised of one or more incompetent or unconsolidated sand layers of zones. The sand particles in the incompetent or unconsolidated sand zone move or migrate into the well bore during recovery of formation fluids from that zone, or sand particles move away from the well during injection of secondary or tertiary recovery fluids into the formation. In the instance of recovering the fluid from the formation, the movement of sand into the well bore can cause the well to cease production of fluids therefrom. Also, small sand particles can plug small openings and porous masses formed around the well bore for the purpose of restraining the flow of sand, such as screens or slotted liners which are frequently placed in wells for this purpose. Not only can fluid production be reduced or even stopped altogether, if sand particles flow through the well to the surface, considerable mechanical problems can result from passage of abrasive sand particles through pumps and other mechanical devices.
Many techniques have been described in the prior art for preventing or decreasing the flow of sand into well in a course of petroleum production, including the use of sand screens, filters, perforated or slotted liners, etc. around the well. These prior art attempts have been successful in some limited instances, but have not always been entirely satisfactory for a number of reasons. Mechanical devices usually restrain only the larger particle sand and are not completely effective for the purpose of restraining or preventing the flow of fine particles from the formation into the well and ultimately to the surface. Furthermore, the devices interfere with various types of completions and work over operations.
Recently, there have been introduced into the market place by numerous oil field companies, chemical compositions which bond the sand grains together with a resinous plastic material to form a permeable mass which effectively restrains the flow of sand particles from the formation. These methods involve injecting into a sand pack around a well bore, a polymerizable, resinous material, which is later caused to polymerize so as to consolidate formation sand or sand packed around the well for that purpose, to form the desired permeable barrier. Numerous difficulties have been encountered in commercial application and use of this technique, including the difficulty of achieving the even polymerization of the resinous material to the degree necessary to consolidate the sand particles while still maintaining the necessary permeability so that petroleum or other fluid may pass therethrough. Furthermore, the resinous materials are expensive. Recently, many tertiary recovery techniques involving the injection of steam or other fluids into the formation for the purpose of mobilizing viscous petroleum, and this has imposed a still greater burden on sand consolidation techniques, and has particularly caused problems with the plastic consolidation techniques which are sensitive to the high temperature, high pH aqueous fluids frequently employed in such processes. The resinous materials are frequently dissolved or degraded by contact with the hot alkaline fluids used intetiary recovery processes.
Serious problems have been encountered in attempting to use conventional sand packs in conjunction with tertiary recovery techniques involving steam injection. Where the high temperature steam or hot water under high flow rates contacts sand packs it has been found that such packs are quickly eroded away or dissolved and must therefore be replaced at frequent intervals.
There is need in the art therefore for a sand pack which when employed, for example, in wells utilized in steam or hot water flooding operations, will have a long operating life.